as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
Never has fandom looked so intriguingly insidious.
—
Michael Cuby, Them., 27 Aug. 2025
Habitat loss has been insidious — croplands have been stripped of their bordering hedgerows and old fields and woodlots have been converted to housing developments.
—Bruce Beehler, Baltimore Sun, 17 Aug. 2025
The simplicity of the scheme What made the fraud so insidious was its simplicity.
—Erik Lie, Fortune, 17 Aug. 2025
Even more insidious is the ability of some perennial weeds to reproduce from little vegetative bits that break off, roll down the hill, and make new problems.
—Paul Cappiello, The Courier-Journal, 15 Aug. 2025
See All Example Sentences for insidious
Michael Cuby, Them., 27 Aug. 2025
Habitat loss has been insidious — croplands have been stripped of their bordering hedgerows and old fields and woodlots have been converted to housing developments.
—Bruce Beehler, Baltimore Sun, 17 Aug. 2025
The simplicity of the scheme What made the fraud so insidious was its simplicity.
—Erik Lie, Fortune, 17 Aug. 2025
Even more insidious is the ability of some perennial weeds to reproduce from little vegetative bits that break off, roll down the hill, and make new problems.
—Paul Cappiello, The Courier-Journal, 15 Aug. 2025
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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Under an imperial decree, her captors become unlikely allies, guiding Jewish refugees through ambushes, shifting alliances and treacherous waters, while Sara confronts leadership, loyalty and love at a high cost.—
Ben Croll,
Variety,
29 Sep. 2025
-
In the cataclysmic civil war at Kuru-kshetra, both the divine Pandava brothers and their treacherous cousins, the Kauravas, end up breaking the rules of war to achieve victory at any cost.—
Seamus Sullivan
September 29,
Literary Hub,
29 Sep. 2025
Adjective
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However, the more subtle aspects of Goodman’s all-around game — pitch calling, receiving, and knowledge of opposing hitters — have been impressive.—
Patrick Saunders,
Denver Post,
27 Sep. 2025
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The roomy primary compartment offers ample space for your phone, wallet, and other sightseeing essentials, while a subtle pocket at the back of the bag is a safe place to store your passport during travel days.—
Merrell Readman,
Travel + Leisure,
27 Sep. 2025
Adjective
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Bondi’s appearance on Fox News comes days after Comey was indicted by a federal grand jury on two of three counts sought by prosecutors, one count of making false statements and one count of obstruction of justice, according to documents.—
Sydney Topf,
The Washington Examiner,
27 Sep. 2025
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Criminal court records reviewed by PEOPLE show the 35-year-old faces charges of public intoxication, disorderly conduct, resisting arrest and a false report.—
Colson Thayer,
PEOPLE,
27 Sep. 2025
Adjective
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Specifically, the four customers argued that Hershey's violated Florida Deceptive And Unfair Trade Practices Act, which is designed to protect Floridians from unfair competition, deceptive acts and unethical practices.—
Greta Cross,
USA Today,
26 Sep. 2025
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In recent years, users have increasingly been taking to court to challenge allegedly deceptive practices by Amazon.—
Winston Cho,
HollywoodReporter,
25 Sep. 2025
Adjective
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Her Ashley is the movie’s fourth and fifth wheel, dismissed as both a perfidious troublemaker and a New Age airhead—a life coach in need of a wife coach.—
Justin Chang,
New Yorker,
22 Aug. 2025
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This perfidious situation, unintentional as its creation may have been, was strongly critiqued as far back as 1983 by Jonathan Crush and Paul Wellings in an article in The Journal of Modern African Studies.—
The Editors,
JSTOR Daily,
15 Aug. 2025
Adjective
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The remarks were interpreted by many on the right as an incorrect classification of Robinson’s beliefs and a direct or indirect placement of blame for Kirk’s murder on extreme-right politics.—
Tony Maglio,
HollywoodReporter,
25 Sep. 2025
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The employee later said Buttgereit had the right to dispute the bill but gave her an incorrect deadline.—
Katheryn Houghton,
Miami Herald,
25 Sep. 2025
Adjective
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Too many projects still aim at the wrong problem from day one.—
Mike Hoffman,
Fortune,
28 Sep. 2025
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Gap Tie-front Woven Maxi Dress A white cotton dress will never steer you wrong.—
Sophie Dodd,
Travel + Leisure,
28 Sep. 2025
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 4 Oct. 2025.
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